Image Processing Reference
In-Depth Information
Enough with theory! How about a real example? The California poppies in Fig-
ure 6.3 show strong chromatic aberration along the edges of the flower petals.
Figure 6.3
The original image shows strong
chromatic aberration on the
edges of the flowers. This is easy
to correct in Camera Raw.
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To start, open the image in Camera Raw and make any major adjustments such
as Exposure, Shadows, and Contrast. To help with your adjustments, turn Sharpening
off in the Detail tab. This will make it easier to tell what is actually chromatic aberra-
tion and what is an artifact of sharpening.
By holding down the Alt/Option key while clicking each of the Chromatic Aber-
ration sliders, you can hide the other color channel to make it easier to see where the
problem areas are. In Figure 6.4 there is an obvious problem in the Blue channel while
the Red/Cyan channel looks fine.
Figure 6.4 (left) Holding down the Alt/Option key while clicking the Fix Red/Cyan Fringe slider hides the Blue channel and shows
that this image has no fringing problems that need correcting in this channel. (right) The same Alt/Option+click combination on
the Fix Blue/Yellow Fringe slider shows strong chromatic aberration along the edge of the flower petals.
Don't be afraid to drag these sliders large amounts if needed. Unlike adjustments
to noise, there is little, if any, image degradation or softening when using the Chro-
matic Aberration controls. The image in Figure 6.5 needed to have a +55 adjustment to
the Fix Blue/Yellow Fringe slider to correct the fringing problems.
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